1. Field of the Invention
The apparatus and methods consistent with the present invention relates to bar code readers or computer terminals connected to wireless networks, and more particularly to the network architecture, configuration software, and inter-network messaging and communications protocols needed to support message services from bar code reader units to mobile units operated in such networks, and from network to network.
2. Background of the Invention
Wireless local area networks use infrared or radio frequency communications channels to communicate between portable or mobile computer terminals and stationary access points or base stations. These access points are in turn connected by a wired (or possibly wireless) communication channel to a network infrastructure which connects groups of access points together to form a local area network, including, optionally, one or more servers or host computer systems.
One type of mobile computer terminal coupled to or incorporating a bar code symbol reader as bar code symbol readers, are now very common for data collection applications. Typically, a bar code symbol comprises one or more rows of light and dark regions, typically in the form of rectangle. The relative widths of the dark regions, i.e., the bars and/or the widths of the light regions, i.e., the spaces, between the bars encode data or information in the symbol.
A bar code symbol reader illuminates the symbol and senses light reflected from the regions of differing light reflectivity to detect the relative widths and spacings of the regions and derive the encoded information. Bar code reading type data input systems improve the efficiency and accuracy of data input for a wide variety of applications. The ease of data input in such systems facilitates more frequent and detailed data input, for example to provide efficient taking of inventories, tracking of work in progress, etc.
A variety of scanning systems are known. One particularly advantageous type of reader is an optical scanner which scans a beam of light, such as a laser beam, across the symbols. Laser scanner systems and components of the type exemplified by U.S. Pat. Nos. 4,387,297 and 4,760,248 which are owned by the assignee of the instant invention and are incorporated by reference herein have generally been designed to read indicia having parts of different light reflectivity, i.e., bar code symbols, particularly of the Universal Product Code (UPC) type, at a certain working range or reading distance from a hand-held or stationary scanner.
Wireless and radio frequency (RF) protocols are known which support the logical interconnection of portable roaming terminals having a variety of types of communication capabilities to host computers. The logical interconnections are based upon an infrastructure in which at least some each of the remote terminals are capable of communicating with at least two of the access points when located within a predetermined range therefrom, each terminal unit being normally associated with and in communication with a single one of such access points. Based on the overall spatial layout, response time, and loading requirements of the network, different networking schemes and communication protocols have been designed so as to most efficiently regulate the communications between a given terminal and the network through the selected access point. One such protocol is set forth in the ISO/IEC 8802-11, or ANSI/IEEE Std 802.11 entitled “Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications” (1999 edition) available from the IEEE Standards Department, Piscataway, N.J. (hereinafter the “IEEE 802.11 Standard”).
Wireless messaging through gateways from the Internet, or LANs, is also known, such as from U.S. Pat. No. 6,178,331. Although such techniques allow messages to be generated manually or automatically, the ability of a user to use a bar code reader as a data source, and to choose from different communications options is limited.
Prior to the present invention, there has not been a simple, automatic data entry technique which would allow a user of a mobile computer to read a bar code symbol and send an alert or a message using the data encoded in the symbol from the computer over a wireless local area network to a destination station.